Valves for use in piston driven machines



19 J. B. OTTEIS'II'AD ET AL I 7 VALVES FOR USE IN PISTON DRIVEN MACHINES Filed Dec. 2, 1964 2 Sheets-Sheet 1 INVENTORS JACKB. 07775 57210 I \gERALD J. FARRELL FRI- 5 Dec. 26, 1967 J.'-B.-OTTESTAD ET L 3,359,867

' v VALVES FOR USE IN PISTON DRIVEN MACHINES I Filed rm. 2, 1964 2 Sheets-Sheet 2 v I INVENTORS JACK 3077557140 GER/1L0 J. FARREL United States Patent 3,359,867 VALVES FOR USE IN PISTON DRIVEN MACHINES Jack B. Ottestad, La Jolla, Calif., and Gerald J. Farrell, Elmhurst, 111., assignors to US. Industries, Inc., New Y orlr, N.Y., a corporation of Delaware Filed Dec. 2, 1964, Ser. No. 415,268 Claims. (Cl. 91-422) This invention relates to valves, and, more particularly, to valves which are particularly well adapted for use in piston-driven machines such as high energy rate forging machines, and the like.

It is a primary object of the present invention to afford a novel valve.

Another object is to afford a novel valve of the check valve type which may be readily opened by the application of outside mechanical or physical force thereto.

A further object is to afford a novel valve of the aforementioned type which is automatically held in a closed position when working fluid pressure on both sides of the valve is equal and the aforementioned external physical force is not applied thereto.

In high energy rate forging machines, and the like, wherein a piston is driven along a path of reciprocation in a cylinder, it is often desirable, at different stages in the operation of the machine, to vent the cylinder through the piston so as to equalize the pressure of the working fluid in both ends of the cylinder. It is an important object of the present invention to enable such venting to be controlled in a novel and expeditious manner.

Another object of the present invention is to afford a novel valve which may be readily mounted in such a piston for effecting the aforementioned control of such venting therethrough.

A further object is to afford a novel valve of the check valve type, which embodies a novel movable valve member therein, which is operable in a novel and expeditious manner to control the opening and closing of the valve.

Another object is to afford a novel valve of the aforementioned type which is practical and efiicient in operation, and which may be readily and economically produced commercially.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and what we now consider to be the best mode in which we have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a fragmentary sectional view of a machine embodying a piston having a valve mounted therein which embodies the principles of the present invention;

FIG. 2 is an enlarged longitudinal sectional view through the valve embodied in the piston shown in FIG. 1; and

FIG. 3 is a view similar to FIG. 2, but showing various parts disposed in different operative position.

A valve 1, embodying the principles of the present invention is shown in the drawings mounted in the piston 2 of a machine 3 to illustrate the preferred embodiment tion in the bottom of the cylinder 5 by a retaining ring ice 7. The'piston 2 includes a piston head 8 mounted on and secured to the upper end of a piston post 9, and is vertically reciprocable between a lowermost position wherein the lower peripheral edge of the head 8 is disposed in sealing abutting engagement with the sealing ring 6, FIGS. 1 and 2, and a raised position wherein the head 2 is disp osecl; in vertically upwardly spaced relation to the sealing ring The cylinder block 4 shown in the drawings is of the type which embodies a storage chamber 10 surrounding the lower end portion of the cylinder 5 for holding a supply of pressurized elastic working fluid, such as, for example, compressed air or compressed nitrogen, or the like, for feeding under the piston 2 to thereby drive it upwardly in the cylinder 5 during operation of the machine 3.

When the piston 2 is disposed in its lowermost position, FIGS. 1 and 2, the engagement of the lower peripheral edge of the head 8 with the sealing ring -6 is effective to seal off the underside of the head 2 from the pressure of the working fluid in the storage chamber 10. In the operation of the machine 3, when it is desired to move the piston 2 upwardly from its lowermost position shown in FIG. 2, pressurized working fluid, such as, for example, the aforementioned compressed air or compressed nitrogen, or the like, may be fed from a suitable source of supply, not shown, through conduits, such as a passageway 11 in the cylinder block 4 and a passageway 12 in the retainer ring 7 into the space or triggering chamber 13 within the sealing ring 6 between the lower face of the piston 2 and the bottom wall of the cylinder 5 defined by the upper face of the retaining ring 7. The working fluid thus fed under the piston 2 is effective to raise the latter off from the sealing ring 6 into upwardly spaced relation thereto, as shown in FIG. 3, to thereby substantially instantaneously subject the lower face of the piston head 8 to the full pressure of the working fluid in the chamber 10, which is effective to drive the piston 2 upwardly in the cylinder 5 at a high rate of speed.

At certain times during the operation of a machine such as the machine 3, such as, for example, when the piston 2 thereof is disposed in its lowermost position prior to actuation thereof, it is desirable to interconnect the portions of the cylinder 5 disposed above and below the piston 2 so as to equalize the pressures in those portions. At other times in the operation of such a machine, such as, for example, during the driving actuation of the piston 2, it is desirable to close off communication between the ends of the cylinder 5 disposed on opposite sides of the piston 2. The valve 1 affords a novel valve for automatically opening and closing communication between the opposite ends of the cylinder 5 at the desired times during the operation of the machine 3.

The valve 1 embodies an elongated housing 15 having a pasageway 16 extending axially therethrough. The housing 15 includes an upper end portion 17 and a lower end portion 18, which, in the assembled valve 1, are

disposed in abutting relation to each other. The upper end portion 17 of the housing 15 is round in transverse cross-section, and the main body portion 19 thereof is of larger outside diameter than the lower end portion 20 thereof, to thereby afford an outwardly projecting,

downwardly facing shoulder 21. Two diametrically opposed openings 22 and 33 extend throughthe lower end portion 20 into communication with the passageway 16 immediately below the shoulder 21. The main body portion 19 of the upper end portion 17 of the housing 15 has external threads 24 formed thereon for a purpose which will be discussed in greater detail presently.'

The lower end portion 18 of the housing 15 is of the same outside diameter as the lower end portion 20 of the upper portion 17 of the housing 15, and terminates at its lower end in a downwardly projecting annular boss 25 disposed in eo-axial relation to the passageway 16. The lower end portion 26 of the passageway 16, which extends through the lowermost portion of the housing 15, is of smaller diameter than the remainder of the passageway 16. The upper end of the lower end portion 18 of the housing 15 terminates in a downwardly and inwardly sloping shoulder which affords an upwardly and inwardly facing annular valve seat 27 for a purpose which will be discussed in greater detail presently.

The upper end portion 28 of the passageway 16, which opens outwardly through the top of the housing 15, is preferably of larger diameter than the lower end portion 26 thereof, but is of smaller cross-sectional size than the intermediate portion 29 of the passageway 16 to thereby afford a radially inwardly, downwardly facing shoulder 36 at the junction of the portions 28 and 29.

An elongated valve 31 is mounted in the passageway 16 in co-axial relation thereto. The lower end portion 32 and the upper end portion 33 of the valve member 31 are complementary in cross-sectional size and shape to the end portions 26 and 28, respectively, of the passageway 16, and the valve member 31 is disposed in the pasageway 16 with the end portions 32 and 33 thereof disposed in the end portions 26 and 28, respectively, of the passageway 16 with a relatively snug but freely slidable fit for reciprocation relative thereto. The valve member 31 also embodies an enlarged head 34 on the intermediate portion thereof, the head 34 affording a substantially radially outwardly projecting, upwardly facing shoulder 35 on the upper end thereof, and a downwardly and inwardly sloping valve seat 36 on the lower end thereof. The valve seat 36 is of such diameter as to sealingly engage the valve seat 27 when the valve member 31 is disposed in its lowermost position in the housing 15, FIG. 3. The valve seat 36 is of such width that, when it is engaged with the seat 27 it projects downwardly and inwardly therepast, as shown in FIG. 3.

The valve member 31 is vertically reciprocable in the passageway 16 between a fully lowered position wherein the valve seat 36 is seated against the valve seat 27 in sealing engagement therewith, as shown in FIG. 3, and a raised position wherein the valve seat 36 is disposed in upwardly spaced relation to the valve seat 27, as shown in FIG. 2. A compression coil spring 37 is disposed around the valve member 31 between the shoulder 30 and the shoulder 35 in position to yieldingly urge the valve member 31, in all positions thereof, downwardly toward a position wherein the valve seats 27 and 36 are disposed in sealing engagement with each other.

The valve 1 is shown in the drawings mounted in an opening 38 extending vertically downwardly into the head 8 of the piston 2, radially outwardly of the piston post 9, FIGS. 2 and 3. When the valve 1 is disposed in operative position in the piston 2, the boss 25 on the lower end portion 18 of the housing 15 is disposed in a complementary recess 39 in the bottom portion 40 of the piston head 8, and the upper end portion 17 of the housing 15 is threaded into position in the opening 38 to clampingly hold the lower end portion 18 of the housing 15 against the bottom portion 40 of the piston head 8. That portion of the upper end portion 17 of the housing 15 disposed above the shoulder 21 fits in the opening 38 with a snug fit, and an air tight seal therebetween is insured by suitable sealing means, such as an O-ring 41 mounted in the outer peripheral edge portion of the upper end portion 17 above the shoulder 23 and disposed in sealing engagement with the inner face of the opening 38. The portion of the upper end portion 17 of the housing 15 disposed below the shoulder 21, and the side Wall portion of the lower end portion 18 of the housing 15, are disposed in radially inwardly spaced relation to the surrounding side wall portions of the opening 38 to aflord an annular passageway 42 extending downwardly around the valve 1 from the passageways 22 and 23 to the bottom portion 40 of the piston head 8, for a purpose which will be discussed in greater detail presently.

The valve member 31 has an elongated passageway 43 extending longitudinally therethrough from the upper end thereof downwardly through the head 34 into the lower end portion of the valve member 31 disposed below the head 34, the passageway 43 terminating in upwardly spaced relation to the reduced lower end portion 32 of the valve member 31. Another passageway 44 extends transversely through the lower end portion of the valve member 31 in communication with the lower end portion of the passageway 43. The transverse opening 44 is so disposed on the valve member 31 that in all operative positions of the valve member 31 the opening 44 is disposed below the upper edge portion of the valve seat 27 on the housing 15.

The intermediate portion 29 of the passageway 16 in the housing 15, and the valve member 31, are of such cross-sectional size that when the valve member 31 is disposed in lowermost position, with the seat 36 thereon disposed in engagement with the seat 27, all portions of the valve member 31 between the shoulder 30 and the restricted portion 26 of the opening 16 except the seat 35, are disposed in radially inwardly spaced relation to the surrounding portion of the housing 15; and when the valve member 31 is disposed in raised position, wherein the seat 36 is disposed in upwardly spaced relation to the seat 27, all portions of the valve member 31 between the shoulder 30 and the restricted opening 26, including the valve seat 36, are disposed in radially inwardly spaced relation to the surrounding portion of the housing 15. The head 34 is disposed on the valve member 31 in such position that when the valve member 31 is disposed in the aforementioned lowermost position, the shoulder 35 thereon is disposed below the passageways 22 and 23, and when the valve member 31 is disposed in fully raised position, the shoulder 35 is at least disposed below the upper edge portions of the passageways 22 and 23. The spacing of the valve member 31 relative to the housing 15 is such that in all positions of the valve member 31 the intermediate portion 29 of the passageway 16 disposed below the shoulder 35 on the head 34 is more restricted by the valve member 31 than is the portion of the intermediate portion 29 disposed above the shoulder 35. Thus, when the valve member 31 is disposed in open position and elastic working fluid is flowing from the passageways 22 and 23 to the passageway 44, the restriction afforded by the head 34 to the flow of working fluid therepast affords a metering of the flow of working fluid so that the pressure of the working fluid on the upper shoulder 35 is greater than the pressure on the lower shoulder or seat 36 and, therefore, is effective to substantially instantly move the valve member 31 into closed position. The spring 37, which at all times urges the valve member 31 toward closed position, assists in closing the valve member 31 under such conditions, and is also effective to normally hold the valve member 31 in closed position When the pressures of the working fluid above and below the head 34 are the same.

On the other hand, when the valve member 31 is disposed in closed position, as shown in FIG. 3, and the pressure of the working fluid in the passageway 44 ex-- ceeds the pressure of the working fluid in the passageways 22 and 23 by a suflicient amount that the upward force exerted thereby on the portion of the Valve seat 36 projecting downwardly below the valve seat 27 will overcome the force afforded by the combination of the downward pressure of working fluid 0n the shoulder 35 and the downward pressure of the spring 37 on the valve member 31, valve member 31 is moved upwardly out of closed position by the pressure of the working fluid below the seat 36 to thereby permit working fluid to flow from the passageway 44 into the passageways 22 and 23.

The upper end portion 33 of the valve member 31 is so constituted and arranged relative to the head 34, that in all positions of the valve member 31 the upper end portion thereof terminates at its upper end in downwardly spaced relation to the upper end of the housing 15. The lower end portion 32 of the valve member 31 is so constituted and arranged relative to the head 34, that when the valve member 31 is disposed in lowermost position, with the seat 36 thereof disposed in engagement with the valve seat 27, the free end portion of the lower end portion 32 projects downwardly below the bottom portion 40 of the piston head 8, FIG. 3. Under such conditions the lower end portion 32 of the valve member 31 projects downwardly below the piston head a suflicient distance that when the piston 2 is moved downwardly into its lowermost position, wherein it is disposed in sealing engagement with the sealing ring 6, the free end of the lowermost portion 32 of the valve member 31 is abuttingly engaged by the bottom of the piston 5 to thereby physically hold the valve member 31 in raised position wherein the seat 36 thereof is disposed out of engagement with the seat 27, FIG. 2.

The bottom portion 40 of the piston head 8 has two passageways 45 and 46 extending upwardly therethrough into communication with the lower end of the opening 38 therein. Thus, when the piston 2 is disposed in lowermost position, wherein it is in sealing engagement with the sealing ring 6, the triggering chamber 13 below the piston 2 is at all times in communication with the portion of the cylinder 5 disposed above the piston 2 through the passageways 45, 46, and 42, and the valve 1. Such construction affords, among other things, a safety device for preventing premature triggering of the piston 2 from its engagement with the sealing ring 6 by the leakage of high pressure working fluid into the triggering chamber 13, this chamber being vented to the upper end portion of the cylinder 5 at all times while the piston 2 is disposed in lowermost position.

During the operation of the machine 3, when the piston 2 is disposed in sealing engagement with the sealing ring 6, and upward movement of the piston 2 is initiated by feeding compressed elastic working fluid through the passageways 11 and 12 into the triggering chamber 13 a portion of this working fluid may flow upwardly through the passageways 45, 46, and 42 and the valve 1 into the portion of the cylinder 5 disposed above the piston 2, the valve 1 being held in open position by the engagement of the lower end portion 32 of the valve member 31 with the bottom of the cylinder 5. However, such flow upwardly through the valve 1 is substantially instantaneously cut olf in the operation of the machine 3, the force exerted on the lower face of the piston 2 :by the highpressure working fluid in the triggering chamber 13 being suflicient that the piston 2 is substantially instantaneously moved upwardly from its lowermost position out of engagement with the sealing ring 6, to thereby move the lower end portion 32 of the valve member 31 upwardly out of engagement with the bottom of the cylinder 5 and release the valve member 31 for movement downwardly into closed position under the urging of the spring 37 and the high pressure working fluid acting upon the shoulder 35 on the top of the head 34. Thus, the valve 1 is closed substantially simultaneously with the initial upward movement of the piston 2 in the cylinder 5 and prevents any substantial flow of working fluid upwardly through the piston 2 during such actuation of the piston 2, the pressure below the piston head 8 being substantially greater than the pressure thereabove during this time.

In certain instances during the operation of a machine such as the machine 3, when the pressure in the cylinder 5 above the piston head 8 rises above the pressure in the cylinder 5 below the piston head 8, such as, for example, during an inching operation wherein the piston 2 is slow- 1y moved upwardly in the cylinder 5, it is desirable to relieve the build up of pressure above the piston 2. The valve 1 affords a novel device of the check-valve type for automatically accomplishing such relief. Thus, when the pressure in the cylinder 5 above the piston 2 is greater than the pressure in the cylinder 5 below the piston 2, the pressure in the passageways 43 and 44 in the valve member 31 and in the portion of the passageway 16 in the housing 15 disposed below the valve seat 36 is greater than the pressure in the housing 15 above the shoulder 35. When this pressure dilferential becomes sufiiciently great that the upwardly acting force on the portion of the valve seat 36 extending downwardly and inwardly from the valve seat 27 is great enough to overcome the downwardly acting force of the spring 37, the valve member 31 is moved upwardly thereby into open position to thereby vent the upper end portion of the cylinder 5 into the lower end portion thereof. The spring 37 is preferably relatively light, so that the pressure differential between the passageway 44 and the passageways 22 and 23 effective to move the valve member 31 upwardly is relatively small. However, it is of suflicient strength to insure that, when the working fluid pressures above and below the head 34 are equal, the valve member 31 is disposed in closed position.

From the foregoing it will be seen that the present invention affords a novel valve of the check valve type, which is particularly well adapted for use in piston type machines wherein it is desired to afford controlled venting of the cylinder portion disposed on opposite sides of the piston.

Also, it will be seen that the present invention affords a novel valve of the check valve type which is practical and eflicient in operation, and which may be readily and economically produced commercially.

Thus, while we have illustrated and described the preferred embodiment of our invention, it is to be understood that this is capable of variation and modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alternations as fall within the purview of the following claims.

We claim:

1. A valve for controlling the flow of working fluid comprising (a) an elongated housing,

(b) said housing having (1) one passageway extending axially therethrough,

(2) one annular valve seat in one end portion of said passageway and facing toward the other end of said passageway,

(3) an annular shoulder in the other end portion of said passageway and facing toward said valve seat, and

(4) a second passageway extending laterally through said housing in communication with said one passageway between said seat and said shoulder,

(c) the outer end portion of said one end portion of said one passageway being of smaller cross-sectional size than the remainder thereof,

(d) an elongated valve member mounted in said one passageway in co-axial relation thereto,

(e) said valve member having (1) a reduced outer end of one end portion thereof slidably mounted in said outer end portion of said one end portion of said one passageway,

(2) the other end portion thereof slidably mounted in said other end portion of said one passagey,

(3) an enlarged head on said one end portion thereof having a second annular valve seat facing toward said one annular valve seat,

(4) a third passageway extending longitudinally through said other end portion thereof and through said head, and

(5) a fourth passageway extending laterally through said one end portion thereof in com munication with said third passageway on the side of said head remote from said other end portion of said valve member,

(f) said head being disposed in such position in said one passageway that 1) when the pressure of such working fluid is greater in said second passageway than in said fourth passageway said pressure is eifective to urge said second seat toward said seating engagement with said one seat for closing communication between said second and fourth passageways and thereby prevent the flow of working fluid through the valve, and

(2) when the pressure of said working fluid is greater in said fourth passageway than in said second passageway by more than a predetermined amount said pressure is effective to urge said second seat away from said first seat for opening communication between said second and fourth passageways and thereby permit the flow of working fluid through said valve,

(g) a tension coil spring disposed around said valve member between said shoulder and said head in position to urge said second valve seat toward said one valve seat, and

(h) said reduced outer end of said valve member projecting outwardly from said housing in position to be pushingly engaged in a direction eflFective to move said second valve seat away from said one valve seat against the urging of said spring and said working fluid in said second passageway.

2. In a machine embodying a supporting member, and an abutment member, with said members relatively movable toward and away from each other,

(a) a valve mounted in said supporting member for controlling the flow of working fluid therethrough,

(b) said valve comprising (1) a housing having a passageway therethrough with opposite ends of said passageway in communication with respective sides of said supporting member,

(2) a valve member mounted in said passageway and movable between an ,open and closed position therein to thereby open and close said passageway to the flow of such working fluid therethrough (3) means in said housing for yieldingly urging said valve member toward said closed position, and

(4) means on said valve member and operatively engaged with said abutment member when said supporting member is disposed in one position relative to said abutment member to thereby hold said valve member in said open position,

() said means on said valve member projecting from one of said sides of said supporting member, and

(d) the pressure of said working fluid on said One side of said supporting member urging said valve member toward said closed position.

3. In a machine as defined in claim 2, and in which (a) said housing has two end portions,

(b) said means on said valve member projects outwardly from one of said end portions, and

(c) said one end portion and said supporting member define a passageway connecting one end of said firstmentioned passageway to said one side of said supporting member.

4. In a machine as defined in claim 3, and in which (a) said end portions of said housing are removable from each other, and (b) the other of said end portions is threadedly engaged with said supporting member in position to clamp said one end portion against a portion of said supporting member.

5. In a machine embodying an elongated cylinder, a piston mounted in said cylinder for reciprocation between the ends thereof, said piston having an opening extending therethrough in substantially parallel relation to the longitudinal axis of said cylinder, and means for feeding Working fluid under pressure between said piston and one of said ends for moving said piston from one position adjacent said one end toward the other of said ends,

(a) an elongated, tubular valve housing mounted in said opening in co-axial relation thereto,

(b) said housing having (1) one end portion spaced radially inwardly from one end portion of said opening,

(2) another end portion sealingly engaged in the other end portion of said opening,

(3) passage means extending laterally through said one end portion thereof into communication with the interior of said housing adjacent the juncture of said end portions thereof, and

(4) an internal valve seat on the side of said passage means remote from said other end portion of said housing,

(0) an elongated valve member having (1) one passageway extending longitudinally through a portion thereof in communication with said other end portion of said housing,

( 2) another passageway extending laterally therethrough into communication with one end of said one passageway on the side of said valve seat remote from said passage means, and

(3) an outwardly projecting head,

(d) said valve member being reciprocable longitudinally of said housing for moving said head into and out of engagement with said seat to thereby close and open communication between said passage means and said other passageway, respectively,

(e) means yieldingly urging said head toward engagement with said seat, and

(f) means, including an end portion of said valve member extending outwardly from said one end portion of said housing in position to abuttingly engage said one end of said cylinder when said piston is disposed in said one position, for holding said head out of engagement with said seat.

References Cited UNITED STATES PATENTS 1/1951 James 137-540 X 1/1964 Kline 91165 1/1964 Combs 91422 FOREIGN PATENTS 12/1936 France. 11/ 1944 Great Britain. 

1. A VALVE FOR CONTROLLING THE FLOW OF WARKING FLUID COMPRISING (A) AN ELONGATED HOUSING, (B) SAID HOUSING HAVING (1) ONE PASSAGEWAY EXTENDING AXIALLY THERETHROUGH, (2) ONE ANNULAR VALVE SEAT IN ONE END PORTION OF SAID PASSAGEWAY AND FACING TOWARD THE OTHER END OF SAID PASSAGEWAY, (3) AN ANNULAR SHOULDER IN THE OTHER END PORTION OF SAID PASSAGEWAY AND FACING TOWARD SAID VALVE SEAT, AND (4) A SECOND PASSAGEWAY EXTENDING LATERALLY THROUGH SAID HOUSING IN COMMUNICATION WITH SAID ONE PASSAGEWAY BETWEEN SAID SEAT AND SAID SHOULDER, (C) THE OUTER END PORTION OF SAID ONE END PORTION OF SAID ONE PASSAGEWAY BEING OF SMALLER CROSS-SECTIONAL SIZE THAN THE REMAINDER THEREOF, (D) AN ELONGATED VALVE MEMBER MOUNTED IN SAID ONE PASSAGEWAY IN CO-AXIAL RELATION THERETO, (E) SAID VALVE MEMBER HAVING (1) A REDUCED OUTER END PORTION OF ONE END PORTION THEREOF SLIDABLY MOUNTED IN SAID OUTER END PORTION OF SAID ONE END PORTION OF SAID ONE PASSAGEWAY, (2) THE OTHER END PORTION THEREOF SLIDABLY MOUNTED IN SAID OTHER END PORTION OF SAID ONE PASSAGEWAY, (3) AN ENLARGED HEAD ON SAID ONE END PORTION THEREOF HAVING A SECOND ANNULAR VALVE SEAT FACING TOWARD SAID ONE ANNULAR VALVE SEAT, (4) A THIRD PASSAGEWAY EXTENDING LONGITUDINALLY THROUGH SAID OHTER END PORTION THEREOF AND THROUGH SAID HEAD, AND (5) A FOURTH PASSAGEWAY EXTENDING LATERALLY THROUGH SAID ONE END PORTION THEREOF IN COMMUNICATION WITH SAID THIRD PASSAGEWAY ON THE SIDE OF SAID HEAD REMOTE FROM SAID OTHER END PORTION OF SAID VALVE MEMBER, (F) SAID HEAD BEING DISPOSED IN SUCH POSITION IN SAID ONE PASSAGEWAY THAT (1) WHEN THE PRESSURE OF SUCH WORKING FLUID IS GREATER IN SAID SECOND PASSAGEWAY THAN IN SAID FOURTH PASSAGEWAY SAID PRESSURE IS EFFECTIVE TO URGE SAID SECOND SEAT TOWARD SAID SEATING ENGAGEMENT WITH SAID ONE SEAT FOR CLOSING COMMUNICATION BETWEEN SAID SECOND AND FOURTH PASSAGEWAYS AND THEREBY PREVENT THE FLOW OF WORKING FLUID THROUGH THE VALVE, AND (2) WHEN THE PRESSURE OF SAID WORKING FLUID IS GREATER IN SAID FOURTH PASSAGEWAY THAN IN SAID SECOND PASSAGEWAY BY MORE THAN A PREDETERMINED AMOUNT SAID PRESSURE IS EFFECTIVE TO URGE SAID SECOND SEAT AWAY FROM SAID FIRST SEAT FOR OPENING COMMUNICATION BETWEEN SAID SECOND AND FOURTH PASSAGEWAYS AND THEREBY PERMIT THE FLOW OF WORKING FLUID THROUGH SAID VALVE, (G) A TENSION COIL SPRING DISPOSED AROUND SAID VALVE MEMBER BETWEEN SAID SHOULDER AND SAID HEAD IN POSITION TO URGE SAID SECOND VALVE SEAT TOWARD SAID ONE VALVE SEAT, AND (H) SAID REDUCED OUTER END OF SAID VALVE MEMBER PROJECTING OUTWARDLY FROM SAID HOUSING IN POSITION TO BE PUSHINGLY ENGAGED IN A DIRECTION EFFECTIVE TO MOVE SAID SECOND VALVE SEAT AWAY FROM SAID ONE VALVE SEAT AGAINST THE URGING OF SAID SPRING AND SAID WORKING FLUID IN SAID SECOND PASSAGEWAY. 